This proposal has the long-term goal of understanding how people with low vision analyze and process two-dimensional layout of images and scenes at multiple scales. The overarching theme of the proposed studies is perception of spatial layout in low vision, particularly on layout in two dimensions such as, for example, perception of a magnified or unmagnified computer screen, or of a monocular image of a visual scene through an optical or video distance telescopic aid. Using subjects with a highly prevalent form of low vision, central visual field loss (CFL), and normally-sighted subjects under both normal viewing conditions and simulated CFL, two main issues will be addressed using psychophysical methods: Global layout perception: Image element identification and accuracy of element localization will be measured with three kinds of (unmagnified) images: web pages, natural urban scenes and colored drawings composed of basic shapes. Exposure duration will also be varied in order to assess the degree to which spatial layout can be retained pre-attentively from glimpses of such images. Linking global and local views: The strategies people use in attempting to link objects in global view to objects they re-image within a magnified image view will be examined, by 1) measuring subjects' accuracy in assessing the amount of magnification required to perform focal visual tasks based on information that is sub threshold with respect to those tasks, by 2) assessing ability to learn to assess magnification needs accurately based on feedback, and by 3) assessing subjects' abilities to gauge direction and size of pointing errors based on feedback from a magnified view, as a function of magnification.